Interaction of Plant Polyphenols with Iron Ions
| Authors | |
|---|---|
| Year of publication | 2004 |
| Type | Article in Proceedings |
| Conference | Vitamins 2004 - Targeted Nutritional Therapy |
| MU Faculty or unit | |
| Citation | |
| Field | Biochemistry |
| Keywords | polyphenols; iron ions; ferrozin |
| Description | Polyphenols are plant secondary metabolites that are a common part of human diet. Some epidemiological studies have suggested an association between the consumption of polyphenol-rich foods or beverages and the prevention of cardiovascular diseases and cancer. These pathological conditions are connected with excessive free radicals production. Formation of free radicals is closely related to the redox state of iron, e.g. ferrous ions are responsible for hydroxyl radical formation by Fenton reaction. Numerous authors have investigated the free radical scavenging activity of plant polyphenols, and several reports have been made to elucidated iron or copper ions chelating ability of polyphenols, although the interaction of plant polyphenols with transient metal ions has not been fully resolved. In this study we investigated the formation of Fe2+ and Fe3+ complexes with naturally occurring polyphenolic compounds above all phenolic acids by spectrophotometric measurement at pH 7.4. The stability of complexes was evaluated after addition of EDTA and ascorbic acid. Influence of ligands on Fe2+ autooxidation and Fe3+ reducing activity of polyphenols was assessed by determination of Fe2+ concentration using ferrozine. Interaction of polyphenolic compounds with iron was compared with that of ascorbic acid and cysteine. Both ascorbic acid and cysteine inhibited Fe2+ autooxidation and reduced ferric ions, and thus tend to stabilize Fe2+ ions. Conversely, most of polyphenolic compounds showed little or no reducing activity on Fe3+ ions and effectively increased the rate of Fe2+ autooxidation. Analyses of interaction of plant polyphenols with iron may be useful for elucidation of their antioxidant effect. |
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